A line with no frame. Neither "remember" nor "consider": one verse is copied out1, and that is all. Such bare quotations run in sequence in Book XI — cf. 11.22–11.25 and the passages that follow this one; the notebook stores material without explaining what for.
The key is the ambiguity of λόγου. TERMΛόγος means both "speech" and "reason." In a tragic context the sense is juridical: a slave has no right to speak, παρρησία is not for him. But Marcus copies the line for himself, and in his vocabulary λόγος is above all reason — the thing by which a human being is defined. Then the verse reads on a second level: "a slave by nature is one who has no share in reason." Neither translation holds the ambiguity: Rogovin chooses "speech," Long "free speech."
Who the slave is. It is on that second level that the line becomes fit for a notebook. In Marcus slavery is not a station but a condition: a slave is one who is twitched at another's direction (the puppet on strings), who speaks not from himself (11.19: μὴ ἀφ’ ἑαυτοῦ λέγειν ἐν τοῖς ἀτοπωτάτοις), who hands his ruling part over to the body (ibid.). A verse spoken in a tragedy about a bondsman turns into a test: have you a share in λόγος — or are you merely reckoned free?
What is not said. Marcus neither transfers the sense nor interprets it — the interpretation is left to the reader, and that is the genre: a blank to be used, not a conclusion. The governing discipline is assent, the sustaining one action.